Combined regulation effects of peanut meal, superphosphate, and carbonized rice husk on green waste composting

The low degradation efficiency and inconsistent product quality of conventional green waste (GW) composting require technological innovation. This study aimed to optimize the use of organic and inorganic bulking agents to improve GW degradation efficiency and product quality. Compound organic and inorganic bulking agents were formulated using peanut meal (PM: 0, 10, and 20 %), superphosphate (SSP: 0, 5, and 10 %), and carbonized rice husk (CRH: 0, 2, and 4 %). Monitoring of composting parameters (temperature, organic matter degradation, humification, bacterial community) and product quality (nutrients, phytotoxicity) identified T5 (10 % PM + 5 % SSP + 4 % CRH) as the optimal compound bulking agent. Compared to the control, T5 significantly prolonged the thermophilic phase by 7 days and produced the highest-quality compost product within just 28 days. T5 extended the thermophilic phase by 7 days, increased the organic matter degradation rate by 27.6 %, reduced the NH₄⁺-N/NO₃^--N ratio by 52.0 %, and increased the HA/FA ratio by 59.4 %. Network analysis revealed that most bacteria have a positive correlation, indicating that symbiotic relationships may exist in the bacterial community. Among them, Sporosarcina is regarded as the dominant species. T5 enhanced the relative abundance of dominant species in the bacterial community, including Sporosarcina and norank_f_Bacillaceae, thus fostering a more uniform bacterial community and improving the biodegradation of GW. This study provided data for the use of PM, SSP, and CRH as organic and inorganic bulking agents, enhancing GW composting efficiency and product quality while offering a feasible solution for the sustainable utilization of agricultural by-products.